Federal Agencies’ Actions to Stop Bird Flu Virus in Dairy Cows

The United States Department of Agriculture (USDA) has recently identified the spread of H5N1 Avian Influenza among cows within the same herd, from cows to poultry, between dairies associated with cattle movements, and cows without clinical signs that have tested positive. USDA will begin taking action on Monday, April 29, to limit its spread and protect livestock health. The agency has also shared its actions with federal partners to avoid the disease.

Meanwhile, USDA and the U.S. Food and Drug Administration (FDA) said that the milk in the retail market is safe to drink through pasteurization.

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Avian influenza viruses in dairy herds

The U.S. Food and Drug Administration (FDA) is closely working with the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), the Centers for Disease Control and Prevention (CDC) and state partners to investigate an illness among dairy cows in multiple states that is causing decreased lactation, low appetite, and other symptoms. On Wednesday, April 17, the agencies confirmed the detection of highly pathogenic avian influenza (HPAI) A (H5N1) viruses in several dairy herds in Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota, and Texas. The HPAI viruses were detected in milk, swabs, and tissue samples collected to diagnose sick cattle on dairy farms, which were unpasteurized.

They said that there is no concern that this circumstance poses a risk to consumer health or affects the safety of the interstate commercial milk supply because products are pasteurized before entering the market.

“The novel movement of H5N1 between wild birds and dairy cows requires further testing and time to develop a critical understanding to support any future courses of action. This Federal Order is critical to increasing the information available for USDA. Requiring positive test reporting will help USDA better under this disease and testing before interstate movement will limit its spread”, said USDA in a press release.

While cases among humans in direct contact with infected animals are possible, partners at the U.S. Centers for Disease Control and Prevention (CDC) believe that the current risk to the public remains low.

APHIS urges dairy cattle producers and those working in or with the industry to share epidemiological information from affected farms, even if they are not planning to move cattle interstate.

In addition, partners in the U.S. Food and Drug Administration released an update on the ongoing work to ensure the continued effectiveness of the federal-state milk safety system.

Mandatory testing and reporting

USDA shared which actions they are taking with federal partners to get ahead of the disease and limit its spread:

Mandatory Testing for Interstate Movement of Dairy Cattle

  • Before interstate movement, dairy cattle are required to receive a negative test for Influenza A virus at an approved National Animal Health Laboratory Network (NAHLN) laboratory.
  • Owners of herds in which dairy cattle test positive for interstate movement will be required to provide epidemiological information, including animal movement tracing.
  • Dairy cattle moving interstate must adhere to conditions specified by APHIS.
  • As will be described in forthcoming guidance, these steps will be immediately required for lactating dairy cattle, while these requirements for other classes of dairy cattle will be based on scientific factors concerning the virus and its evolving risk profile.

Mandatory Reporting

  • Laboratories and state veterinarians must report positive Influenza A nucleic acid detection diagnostic results (e.g. PCR or genetic sequencing) in livestock to USDA APHIS.
  • Laboratories and state veterinarians must report positive Influenza A serology diagnostic results in livestock to USDA APHIS.

The Milk in The Retail Market Is Safe to Drink

The FDA and USDA said that the commercial milk supply is safe because of the pasteurization process and that milk from sick cows is being diverted or destroyed. The federal-state milk safety system and the Grade “A” Pasteurized Milk Ordinance have proven effective for decades against various pathogens. Data from previous studies shows that pasteurization is very likely to inactivate heat-sensitive viruses in fluid milk effectively. Furthermore, thermal inactivation of HPAI has been successful during the pasteurization process for eggs, which occurs at lower temperatures than what is used for fluid milk.